Ron Paul’s campaign ads have been consistently excellent and his latest — entitled “Etch a Sketch” — is no exception. The ad features skillful editing, limited-but-powerful use of text, tasteful visual effects and a memorable message. The ad reminds us: The problems the nation faces are greater than political games.

Unfortunately for Mr. Paul, clever ads and circumspect statements do not a successful candidate make. Paul has been plagued by his own positions since the beginning of the primary process — and he’ll be plagued by them until the end. It’s not that they’re invalid; it’s that they’re simply not shared by a large enough percentage of the GOP or the nation at large. Ron Paul hasn’t won a single primary or caucus and has spent a whopping $686,000 a delegate, whereas Rick Santorum has spent just $52,000 a delegate, Mitt Romney has spent $187,000 and Newt Gingrich has spent $248,000.

This advertisement — with its lack of attack on Romney — might also contribute to the general perception that Paul will not criticize Romney with as much vigor as he might were it not for his purported concern for the political prospects of his son Rand. Then again, perhaps the Pauls and the Romneys just get along. Ann Romney has openly admitted that Carol Paul is her favorite fellow First Lady wannabe, for example.

But what of the substance of the advertisement, the argument that it is somehow irresponsible for Santorum and Gingrich to mock Eric Fehrnstrom’s thoughtless “Etch a Sketch” remark? At this point in the primary, can Santorum and Gingrich be excused for wanting to do whatever they can to thwart Romney from the nomination?

Negative campaigning works. However much we all profess to hate it, we still respond to it — and usually as the negative campaigner hopes we will respond. We thus induce politicians to continue to use cheap tricks and attack ads. The heat that Santorum and Gingrich have brought to their lampooning of the “Etch a Sketch” comment show that they still deeply — even desperately — desire the nomination or, at least, still deeply desire to deny it to Romney. That is something to consider — and not necessarily something for which to despise them. Romney has been virulent in his attacks on them, too, remember.

All of these attacks are OK as long as those making them and those of us observing them remember all the GOP candidates are on our side in an important respect. They want Obama out of office as badly as we do. They want him out of office even more than do those heroes of the party who declined to run. They want him out of office badly enough to give their time and money to this primary process and to face the prospect of an infinitely harsher general election.

The attacks aren’t OK if they let Obama off the hook in any way. Does calling Romney “the Etch-a-Sketch candidate” encourage him to be evermore consistent in his positions on Obamacare and the bailouts? Then, by all means, call him “the Etch-a-Sketch candidate.” But does it obscure the reality that Obama is the biggest flip-flopper of all? Then, knock it off and remind voters that Obama is the one who is not to be trusted.

Politics are messy, but they need not be purposeless. The overarching purpose of this primary and the November election is to select a president who will uphold the U.S. Constitution and faithfully execute the laws. That’s not Obama. His signature legislative achievement is unconstitutional, his Department of Justice allowed an illegal gunrunning operation to occur on its watch and he routinely legislates through the executive branch. But — it very well could be “Etch a Sketch” Mitt Romney, “carnival barker” Rick Santorum, “granddaddy of earmarks” Newt Gingrich or even “outside-the-mainstream” Ron Paul. Mean nicknames don’t make the men any less qualified — and insincere, slick-sounding messaging doesn’t make Obama any more deserving of a second term.